Silagy 2002.

Methods	Investigated discrepancies between systematic review protocols and published systematic reviews.
Data	N = 47 systematic reviews Inclusion criteria: All new Cochrane Reviews appearing for the first time in the Cochrane Database of Systematic Reviews, Issue 3, 2000; Protocol published for the review in the previous issue of the Cochrane Database of Systematic Reviews, Issue 2, 2000. Exclusion criteria: Updated Cochrane Reviews appearing in the Cochrane Database of Systematic Reviews, Issue 3, 2000. Year(s) of publication of the systematic reviews: 2000 Areas of health care addressed by the systematic reviews: Various (not specifically assessed) Methodological quality of systematic reviews: Not assessed Number (proportion) of systematic reviews that only included RCTs: Not assessed Number (proportion) of systematic reviews that are Cochrane Reviews: 47 (100%) Extent of overlap of RCTs included in the systematic reviews in the empirical study: Not assessed, though unlikely to have impacted on the results
Comparisons	Systematic review protocols versus published systematic reviews
Outcomes	Prevalence of systematic reviews which: added new outcomes from the protocol to the published review; added new measurement methods for existing outcomes from the protocol to the published review; omitted outcomes from the protocol to the published review; made changes to any of the different sections (i.e. background, objectives, types of studies, types of outcomes, etc.) of the protocols and reviews based on the results (as reported by authors when contacted to provide reasons for changes).
Notes	Additional outcomes measured but not included in the review were the prevalence of systematic reviews with discrepancies in sections other than outcomes and analyses (i.e. background section, search strategy). Study published as a journal article and conference abstract. No additional data retrieved from authors.
Risk of bias
Item	Authors' judgement	Description
Is the empirical study at low risk of selection bias?	Yes	Quote: "We identified 66 completed reviews appearing for the first time in the Cochrane Library; 2000, issue 3. Of these, we found a protocol for 71% (n = 47) in 2000, issue 2, of the Cochrane Library. None of these published protocols had any external comments or criticisms attached. The remaining 19 reviews had apparently been carried out without prior publication of a protocol." Comment: This empirical study included all Cochrane Reviews published in a single issue of The Cochrane Library that had a published protocol.
Is the empirical study at low risk of selective reporting bias?	Unclear	Comment: No protocol for the study is available so it is unclear whether all measured and analysed outcomes were reported in the publication.